After a break-up with with your spouse, significant other or love of your life, you might try to remain friends with your ex, slowly cut off contact, or torch every last relic of the relationship.

But one thing is inevitable: Eventually you have to move on. So why is it that some people have a hard time letting go, months or even years after ending a relationship? Although it's natural to mourn the loss of a relationship, some people take such feelings too far.

***

The addictive nature of love is highlighted in research conducted by Helen E. Fisher, Ph.D., a professor of anthropology at Rutgers University and author of "Why We Love: The Nature and Chemistry of Romantic Love."

When Fisher applied brain-imaging technology to a group of volunteers looking at photos of their romantic partners, she discovered that the areas of the brain that lit up were the same as those that corresponded to drug addiction.